QuickBooks multi user mode not working, multiple users to access and work on a company file simultaneously. If it's not working, common issues include network connectivity problems, incorrect hosting settings, or outdated QuickBooks versions. Ensure the server computer is hosting the file and that all users have the necessary permissions. Verify that QuickBooks Database Server Manager is running and check firewall settings. Updating QuickBooks to the latest version and troubleshooting network issues can help resolve multi-user mode problems. For persistent issues, consult QuickBooks support or a certified professional for assistance at 1.855.409.2300.